Stacking unit comprising at least one chamber for housing a food product such as ham

ABSTRACT

A stackable unit includes at least one cell for carrying a foodstuff during cooking. The cell includes a pressing structure for causing pressing of a foodstuff contained in a corresponding cell of a second identical stackable unit of a lower rank, the stackable unit including a support structure for seating the stackable unit on the second identical stackable unit and a centering structure for laterally positioning the stackable unit during stacking thereof on the second identical stackable unit such that the stackable unit can be disposed vertically in line with the second stackable unit. During stacking, a guidance structure guides the stackable unit onto the second identical stackable unit in at least one plane containing the vertical stacking direction.

The present invention concerns a stackable unit comprising at least onecell intended to contain a foodstuff such as ham during its cooking.

In order to carry out the industrial cooking of ham, cooking it in acooking chamber of relatively large volume is known. The hams arewrapped respectively in cooking bags which should be disposed in cellsforming a cooking mould of a stackable unit.

When this first stackable unit is full, it serves as a support for otherstackable units which in that case should be filled and then stackedsuccessively one upon another in order to form a stack which is nexttransferred into a cooking chamber. In certain cases when, for example,the cooking is carried out in a cooking chamber containing aheat-conducting fluid, the stacking is performed inside the cookingchamber by means of a manipulator robot.

In order to allow the shaping of the ham during its cooking, each cellcomprises on its bottom a pressing means intended to press a hamdisposed in a cell of another stackable unit of a lower rank. Thispressing means consists for example of a plate mounted fixed on thebottom of a cell. The last stackable unit stacked is generally empty andserves only as a pressing means for the stackable unit of the lowerrank.

In view of the large mass of a stack of stackable units, it is importantto position a stackable unit accurately with respect to anotherstackable unit of a lower rank so that the pressing means of saidstackable unit can press properly, that is to say repetitively, the hamsof the stackable unit of a lower rank.

Furthermore, in order to obtain gains in productivity, the manipulatorrobots responsible for performing the transfer of the stackable units,and in particular their stacking, work at high speed and therefore causeswaying of the stackable units which still persists at the time of theirstacking.

Although equipped with positioning means, the known stackable units donot allow sufficient positioning accuracy to be obtained between themduring their stacking.

The aim of the invention is therefore to propose in particular astackable unit whose novel construction makes it possible to overcomethese drawbacks.

More particularly, the invention proposes a stackable unit of the typewhich comprises at least one cell intended to contain a foodstuff suchas ham during its cooking, said or each cell being equipped with apressing means provided for allowing the pressing of a foodstuffcontained in a corresponding cell of another identical stackable unit ofa lower rank, the stackable unit being equipped with support meansintended to allow the seating of the stackable unit on another identicalstackable unit, and centring means intended to allow the lateralpositioning of the stackable unit during its stacking on anotheridentical stackable unit in such a way that the stackable unit can bedisposed vertically in line with said other stackable unit.

In order to achieve the above-mentioned aim, this stackable unit ischaracterised in that it comprises guidance means provided for allowing,during the stacking of said stackable unit on another identicalstackable unit, the guidance of the stackable unit in at least one planecontaining the vertical stacking direction.

According to another characteristic of the invention, said guidancemeans are provided for guiding said unit in two planes perpendicular toeach other and containing said stacking direction.

According to another characteristic of the invention, the centring meansare provided for acting in two directions perpendicular to each otherand perpendicular to said stacking direction.

According to another characteristic of the invention, said guidancemeans consist of at least one wall of each foot, said or each wallextending in a direction parallel to the stacking direction and beingcapable of cooperating with at least one guidance element of said unit.

According to another characteristic of the invention, each guidanceelement is formed on gripping means which said stackable unit comprises.

According to another characteristic of the invention, each guidanceelement is formed by a pin which said stackable unit comprises.

According to another characteristic of the invention, the guidance meansare constituted by the rear faces of each foot, said faces beingprovided for cooperating respectively with plates of another stackableunit of lower rank.

According to another characteristic of the invention, the guidance meansare constituted by the rear faces of arms of gripping means which saidstackable unit comprises, said faces being intended to cooperaterespectively with plates of another stackable unit of higher rank.

The characteristics of the invention mentioned above, as well as others,will emerge more clearly from a reading of the following description ofan example implementation, said description being given in connectionwith the accompanying drawings, amongst which:

FIG. 1 a depicts a perspective view of a stackable unit of a first typeaccording to the invention;

FIG. 1 b depicts a perspective view of a stackable unit of a second typeaccording to the invention;

FIG. 2 depicts a schematic front view of a stackable unit in the processof being stacked on another stackable unit of a lower rank;

FIG. 3 depicts a front view of a stackable unit according to theinvention, the left-hand part being a partial section at cell level;

FIG. 4 a depicts a front view of a stackable unit in the phase ofcentring on a stackable unit of a lower rank according to the invention;

FIG. 4 b depicts a front view of a stackable unit at the beginning ofthe phase of guidance onto a stackable unit of a lower rank according tothe invention;

FIG. 4 c depicts a front view of a stackable unit in the position ofabutment on a stackable unit of a lower rank according to the invention;

FIG. 5 depicts a partial side view of a stackable unit in the process ofbeing stacked on another stackable unit of a lower rank according to theinvention;

FIG. 6 depicts a partial front view of a stackable unit equipped with avariant implementation of guidance means;

FIG. 7 a depicts a partial front view of a stackable unit at thebeginning of the guidance phase according to another embodiment of theinvention; and

FIG. 7 b depicts a partial front view of the same stackable unit in theabutment position.

The invention which is described below is in connection with the cookingof ham. It should be understood that it can apply to other types offoodstuff.

FIG. 1 a depicts two stackable units 100 and 100′, according to a firstembodiment, stacked one upon the other. As for FIG. 1 b, this alsodepicts two stackable units 100 and 100′ but according to a secondembodiment.

Each of the stackable units 100 and 100′ depicted in FIGS. 1 a and 1 bcomprises a frame 120 whose sides consist of two transverse plates 122 aand 122 b disposed facing each other. In the embodiment of FIG. 1 a, theplates 122 a and 122 b are joined together at their ends by twolongitudinal side pieces 124 a and 124 b. At least one cell 130 ismounted inside the frame 120 in such a way that its longitudinal axis isparallel to the transverse plates 122 a and 122 b in the exampleimplementation of FIG. 1 a, or perpendicular to the plates 122 a and 122b in the example implementation depicted in FIG. 1 b. FIG. 1 a depicts,for the sake of clarity of the figure, only two cells 130, whereas FIG.1 b depicts six of them.

Each cell 130 is intended to receive a foodstuff, in particular ham,which in general, but not necessarily, is first wrapped in a cookingbag, for its cooking in a cooking chamber. Each cell 130 also compriseson its bottom a pressing means 132 consisting, for example, of a coverprovided for entering another corresponding cell of a stackable unit oflower rank so as to be able to press, during its cooking, the foodstuffsituated therein.

It should be noted that several stackable units 100 which are stackedone upon another are introduced into a cooking chamber.

In view of the large mass of a set of stackable units 100 (a stack ofstackable units 100 can weigh several thousand kg), it is important toposition a stackable unit 100 accurately during its stacking on anotherstackable unit 100′ of a lower rank. This positioning accuracy must besuch that, during the stacking of the stackable unit 100, the pressingmeans 132 of a cell 130 of the stackable unit 100 can uniformly pressthe foodstuffs J disposed in the corresponding cell 130 of the otherstackable unit 100′ of a lower rank.

The object of the invention is to propose means which make it possibleto obtain this accurate positioning.

FIG. 2 depicts a schematic front view of a stackable unit 100 in theprocess of being stacked on another stackable unit 100′ of a lower rank,each of said units 100 and 100′ having the means of the invention. Eachstackable unit 100 comprises support means 160 and 170 provided forallowing its positioning height-wise on the stackable unit 100′. Thesupport means 160 and 170 are separate components and respectivelyconsist of abutment means 160, here shown schematically by horizontallines 160, and holding-up means 170, here shown schematically by otherhorizontal lines 170. Advantageously, four abutment means 160 and fourcorresponding holding-up means 170 are disposed respectively in pairsdistributed over two opposite sides 122 (or 124) of the frame 120 ofeach stackable unit 100. Only two abutment means 160 and two holding-upmeans 170 are visible in FIG. 2.

It should be understood that each abutment means 160 of a stackable unit100 is intended to cooperate with a holding-up means 170 of anotherstackable unit 100′ of a lower rank.

The stackable unit 100 also comprises centring means intended tocorrect, if necessary, its lateral positioning with regard to the otherstackable unit 100′ during its stacking, so that the frames 120 and 120′of the stackable units 100 and 100′ can be disposed in line with eachother.

As can be seen in FIG. 2, the centring means consist of at least twocentring ramps 154 a and 154 b forming respectively an acute angle Cwith the vertical stacking direction T and which are intended tocooperate, during a centring phase of the stacking, respectively withcentring elements 175 a and 175 b, depicted here by simple points, of astackable unit 100′ of lower rank identical to the unit 100.

The stackable unit 100 also comprises guidance means allowing themovement in a vertical stacking direction T of the stackable unit 100during its stacking on a stackable unit 100′ in order in particular toallow said or each pressing means 132 to enter its respective cell 130without touching it.

As can be seen in FIG. 2, these guidance means consist, on the one hand,of first guidance elements 157 a and 157 b and, on the other hand, ofsecond guidance elements 172 a and 172 b. The first guidance elements157 a and 157 b are intended to respectively slide, during a guidancephase of the stacking of the stackable unit 100 on the stackable unit100′, over the second guidance elements 172 a and 172 b of the stackableunit 100′ of lower rank.

A description will now be given of specific embodiments of the supportmeans, the centring means and the guidance means of the inventionadvantageously adapted not only to the stacking of the stackable unitswith one another but also to their manipulation.

In general terms, in order to allow its manipulation, for example by amanipulator robot, with a view, before cooking, to its placing onanother stackable unit or, after cooking, to its withdrawal from thisother stackable unit, each stackable unit 100 comprises, as depicted inFIGS. 1 a and 1 b, at least two gripping means 140 which are disposedrespectively above the cells 130 and which are for example intended tobe coupled to a lifting means, not depicted, of a manipulator robot.These gripping means 140 are for example disposed symmetrically withrespect to said stackable unit 100 and are fixed respectively to twoopposite sides of the frame 120, in this case to the transverse plates122 a and 122 b and on the outside of the frame 120.

FIG. 3 shows an example implementation of a gripping means 140 accordingto an advantageous embodiment of the invention. It consists of a bar 142fixed at its free ends to two arms 144 a and 144 b consistingrespectively of metal strips which are formed by folding and which arethemselves fixed by welding to said opposite sides of the frame 120, inthis case to the transverse plates 122 a and 122 b. Each arm 144 a or144 b is bent so as to have a substantially horizontal part 170 whichwill constitute the holding-up means mentioned above in connection withFIG. 2. The horizontal part 170 of each arm 144 a and 144 b is continuedupwards by a part 172 a or 172 b disposed parallel to the verticalstacking direction T which will constitute, as will be understoodsubsequently, guidance elements as mentioned above in connection withFIG. 2. The guidance part 172 a or 172 b is itself continued by aninclined part 171 a or 171 b which forms an acute angle C′ with thevertical stacking direction T and will constitute other guidanceelements as mentioned above in connection with FIG. 2. In addition, thehorizontal part 170 of each arm 144 a, 144 b is continued downwards by awall 174 a, 174 b, the bend 175 of which, formed with the part 170, willconstitute, as will be understood subsequently, a centring element asmentioned above in connection with FIG. 2.

In general terms also, in order to raise a stackable unit 100 when it isresting on the ground so as to allow the passage of a lifting means,such as the forks of a lift-truck, this stackable unit 100 alsocomprises feet 150, as can be seen in FIGS. 1 a and 1 b. In reality,each stackable unit 100 comprises four feet 150 which are disposedsymmetrically on the stackable unit 100 and which are fixed in pairsrespectively to the same two opposite sides of the frame 120 to whichthe two gripping means 140 are fixed.

More specifically, as can be seen in FIG. 3, each foot 150 consists of ametallic support advantageously consisting of a metal strip folded so asto form a seating wall 155 intended to rest on the ground, and a firstand a second post 151 and 152. The free ends of the first post 151 andof the second post 152 are fixed, for example by welding, to one of thesides of the frame 120. The post 152 comprises, from the seating face155, an inclined wall 154 a, 154 b forming an acute angle C with thestacking direction T. This wall 154 a, 154 b will constitute a centringramp as mentioned above in connection with FIG. 2. This wall 154 a, 154b is continued by a vertical wall 156 a, 156 b (constituting a guidanceelement), and then by an abutment wall 160 (constituting abutment means)disposed in a horizontal plane. This abutment face 160 is also continuedupwards by a guidance wall 157 a, 157 b disposed parallel to thevertical stacking direction T and which will constitute a guidanceelement as mentioned above in connection with FIG. 2. At theintersection of the wall 156 a, 156 b with the wall 160, there is a bend158 a, 158 b which, as will be understood subsequently, will constitutea centring element like that mentioned above in connection with FIG. 2.

Advantageously, in order to improve the mechanical strength of the feet150 during stacking of the stackable units 100, the two posts 151 and152 are not parallel to each other. The posts 151 and 152 of a foot 150are also joined together by a reinforcing bar 153 welded by its ends tosaid posts 151 and 152.

The operation of a stackable unit 100, during its stacking on anotherstackable unit 100′, is now described.

A first stackable unit 100′ filled with ham ready to be cooked isavailable. A second stackable unit 100, also filled with ham ready to becooked, is next stacked on the stackable unit of lower rank 100′.

As the stacking proceeds, the centring means come into operation, asdepicted in FIG. 4 a. As can be noted, the inclined walls 154 a or 154 bcan cooperate respectively with the centring bends 175 a or 175 b so asto bring the stackable unit 100 back into a position where it hangs overthe unit 100′ of lower rank. Similarly, the inclined walls 171 a or 171b can cooperate with the bends 158 a or 158 b of the feet 150. Thus,this makes it possible to position and centre the frame 120 of thestackable unit 100 in line with the frame 120′ of the stackable unit100′. In this way, the risks of incorrect positioning of the stackableunit 100 on the stackable unit 100′ of lower rank are removed or at thevery least considerably reduced.

Once this centring phase has been carried out, the guidance means comeinto operation, as depicted in FIG. 4 b. As can be noted, the walls 157a and 157 b of the feet 150 slide respectively along the walls 172 a and172 b of the gripping means 140. Similarly, the walls 156 a and 156 b ofthe feet 150 slide along the walls 174 a and 174 b of the gripping means140. The guidance means thus allow an accurate movement in a verticalstacking direction T of the stackable unit 100 during its stacking onthe stackable unit 100′. Therefore, the pressing means 132 of thestackable unit 100 can be guided at the moment of their introductioninto the corresponding cells 130 of the stackable unit 100′ withoutcatching the rims of said cells 130.

At the end of the guidance phase, as can be seen in FIG. 4 c, theabutment means 160 of the stackable unit 100 settle on the holding-upmeans 170 of the stackable unit 100′ of lower rank. There, in thisposition, the pressing means 132 press the hams contained in thestackable unit 100′.

It should be noted that the distance d separating a plane passingthrough the abutment surface defined by the abutment means 160 and aplane passing through the holding-up surface defined by the holding-upmeans 170 is equal to the height h₁₃₂ of a cover 132 added to the heighth_(j) of the foodstuff when the latter is pressed, with the thickness ofthe metal sheet constituting the bottom of the cell 130 added to it, ascan be seen in FIG. 4 c. It should be noted that the height h₁₃₂ of thecover 132 is the name given to the distance which separates its activeface and the bottom of the corresponding cell 130.

So as to provide an accurate positioning of a stackable unit 100 onanother stackable unit 100′, these units 100 and 100′ mustadvantageously be able, during their stacking, to be centred and guidedwith respect to each another, both in a plane parallel to the walls 122a and 122 b (see FIGS. 1 a and 1 b), and also in a plane perpendicularto these walls 122 a and 122 b. The invention provides such centringmeans and such guidance means, these means being described in connectionwith FIG. 5.

FIG. 5 depicts, seen from another angle, a stackable unit 100 during thephase of stacking on another stackable unit 100′ of a lower rank.

The centring means consist, on the one hand, of bevelled walls 146implemented respectively on the faces turned towards the frame 120 ofthe arms 144 a and 144 b of the gripping means 140 and, on the otherhand, of bevelled walls 159 implemented respectively on the faces turnedtowards the frame 120 of the feet 150. The walls 146 and 159 areintended to cooperate respectively with the lower edges of the sides ofthe frame of a stackable unit of higher rank and with the upper edges ofthe sides of the frame 120′ of a stackable unit 100′ of lower rank.

As for the guidance means, these are constituted, on the one hand, bythe rear faces 148 of the arms 144 a, 144 b of each gripping means 140and, on the other hand, by the rear faces 162 of each foot 150. The rearfaces 148 and 162 are intended to cooperate respectively with sides ofthe frame 120 of a stackable unit of higher rank and sides of the frame120 of a stackable unit 100′ of lower rank.

The rear faces 148 and 162 thus make it possible to guide the stackableunit 100 during its stacking on a stackable unit 100′ of lower rank. Therear faces 148 and 162 are also offset from the faces of the sides ofthe frame 120 to which they are welded in order to lead to playnecessary for the guidance and also avoid the jamming of the arms 144 aand 144 b and the posts 151 and 152 on fixing welds for the arms 144 aand 144 b and posts 151 and 152 of another stackable unit of higher rankor of lower rank.

So as to allow an accurate relative positioning of the gripping means140 and the feet 150 on the stackable unit 100 before welding themthereto, the arms 144 a and 144 b and the posts 151 and 152 compriserespectively, as can be seen in FIG. 5, centring studs 240 and 250 whichare intended to be positioned respectively in corresponding positioningholes 242, 252, implemented in sides of the frame 120. These centringstuds 240 and 250 are advantageously implemented in the metal stripswhich constitute the feet 150 and the gripping means 140 by a lasercutting method.

FIG. 6 depicts a variant implementation of a stackable unit 100 notcomprising gripping means as in the preceding embodiment. In thisembodiment, the holding-up means 170 are embodied by a generator of apin 180, this generator being intended to receive the wall 160 of a foot150 of a stackable unit of higher rank. There has been depicted indotted lines the pin 180′ of a stackable unit 100′ (not depicted) onwhich the wall 160 rests. It therefore constitutes, with the wall 160,holding-up means according to the present invention. Similarly, agenerator 172 of the pin 180 is provided in order to be able to slidealong the wall 156 a, 156 b of a foot 150 (as shown schematically by thepin 180″ in dotted lines). It then constitutes guidance means accordingto the invention. This same pin 180 is also intended to slide along thewall 154 of a foot 150, as shown schematically by the pin 180′″ indotted lines. It therefore also constitutes centring means according tothe invention.

FIGS. 7 a and 7 b depict another embodiment of a stackable unit (heretwo units 100 and 100′ in the process of being stacked in FIG. 7 a andstacked in FIG. 7 b) according to the present invention. Each unitcomprises feet 150 which have the shape of a U with the corners slightlytruncated. They comprise in particular a guidance element 157. Thesefeet 150 have the advantage of having a symmetrical shape so that aright foot can also be suitable for a left foot and vice versa.

Each stackable unit also comprises gripping means 140 which comprise aninclined wall 171 which constitutes means of centring the unit in orderto provide its lateral positioning with respect to another lowerstackable unit during its stacking thereon.

The gripping means 140 also comprise a guidance element 172 which isintended to cooperate with the guidance element 157 so as to slide withrespect to each other during a phase of guidance of the stackable unit100 during its stacking on the stackable unit 100′, as can be seen inFIG. 7 a. It should be noted that this guidance phase takes place afterthe centring phase and before the seating of the unit 100 on the unit100′ and that it allows each pressing means 132 to enter its respectivecell 130 without touching it.

Each foot 150 also comprises a seating wall 155 which, as will beunderstood, also constitutes an abutment means 160 in the sense of thepreceding embodiments (this explains its dual reference).

Inside each foot 150 there is provided a pillar 180 substantiallyparallel to the stacking direction whose lower end is fixed to theseating wall 155 and whose upper end 181 constitutes the holding-upmeans 170 in the sense of the preceding embodiments (this explains itsdual reference).

As can be noted in FIG. 7 b, the lower face of the seating wall 155 ofthe stackable unit 100 rests on the upper end 181 of the pillar 180. Theone and the other therefore clearly respectively constitute abutmentmeans and holding-up means.

The advantages resulting from this embodiment are as follows. The doublebends which characterise the feet 150 and the gripping means 140 of thepreceding embodiments can prove difficult to implement if accuracy inthe positioning of a stackable unit with respect to the one situatedbelow it is sought, an accuracy which, for example, can be of the orderof a tenth of a millimetre. However, this embodiment does not have thesedouble bends. Moreover, the positioning accuracy is provided by the factthat it is relatively easy to implement the pillar 180 with greataccuracy, of the order of 1/10 mm, in particular its height. Now, it isthis height which determines the positioning between two stackableunits: the distance which separates two stackable units which arestacked one upon the other is equal to the height of the pillar 180added to the thickness of the metal sheet which constitutes the seatingwall 155.

According to an advantageous embodiment of a pillar 180, the latter hasa cross-shaped section which has the effect of increasing its inertiaand its resistance to bending. Furthermore, its end resting on theseating wall 155 is tapered so as to make its lower end accessible forcleaning.

In a variant implementation of the pillar 180, depicted in the inset ofFIG. 7 aa, it has a U-shaped section for the same reasons as thosementioned above. Similarly, the lower ends of the wings of the U aretapered.

As can be noted in the insets accompanying FIG. 7 a, the feet 150comprise centring studs 240 going into positioning holes 242 whosedimensions are such that there is a relatively large amount of play inthe direction parallel to the stacking direction. As for the pillar 180,it comprises a centring stud 182 going into a positioning hole 183 withno play. It is therefore the pillar 180 which provides the accuratepositioning of the seating wall 155 relative to the frame of thestackable unit under consideration.

In order that each foot 150 which is disposed on the frame 120 obstructsnone of the ends of the pressing means 132, which would make theircleaning difficult, for example, with a high-pressure washing appliance,the distance separating the first post 151 from the second post 152 of afoot 150 is greater than the width of a pressing means 132 (see FIGS. 3and 6).

For the same reasons, the arms 144 a and 144 b of the gripping means 140as well as the posts 151 and 152 of the feet 150 are mounted on edge onthe frame 120 and are for example welded thereto.

The stackable unit 100 also comprises holes 126 (see in particular FIG.3) implemented through the sides of the frame 120, and in this case thetransverse plates 122, so as to allow the passage of a sensor into thecells 130 in order to measure, in particular, the cooking temperatureinside the ham J.

The presence of projections 128 which are formed on sides of the frame120 towards the outside of the stackable unit 100 should also be noted.These projections 128 make it possible to house the sealed ends of somecooking bags P1.

Furthermore, and in order to meet the wishes of consumers, it seemedadvantageous to offer hams of different sizes which should be cooked instackable units of different types whose cells 130 have a shape anddimensions which are different from one type of stackable unit toanother.

Thus, the stackable units 100 depicted in FIG. 1 a are of a first type,in which each cell 130 has a bottom of rounded section, and eachpressing means 132 has an abutment face also of rounded section. Eachcell 130 of this stackable unit 100 has a very high rim 134, whichforces guidance of the pressing means 132 for longer. On the other hand,the stackable units 100 depicted in FIG. 1 b are of a second type, inwhich each cell 130 has a prismatic section, and each pressing means 132has a flat abutment face.

The stackable unit of the invention consists essentially of standardelements common to the different types of stackable unit.

Its manufacturing cost is lower than that of a known stackable unit.

It makes it possible to obtain great accuracy of pressing of hams duringtheir cooking.

1-30. (canceled)
 31. A stackable unit comprising at least one cell forcarrying a foodstuff during cooking, said at least one cell including apressing structure for causing pressing of a foodstuff contained in acorresponding cell of a second identical stackable unit of a lower rank,the stackable unit including a support structure for seating thestackable unit on the second identical stackable unit, a centeringstructure for laterally positioning the stackable unit during stackingthereof on the second identical stackable unit in such a way that thestackable unit can be disposed vertically in line with said secondstackable unit, and a guidance structure for guiding during stacking ofsaid stackable unit on the second identical stackable unit, thestackable unit in at least one plane containing the vertical stackingdirection.
 32. The stackable unit of claim 31, wherein said guidancestructure is arranged for guiding said unit in two planes perpendicularto each other and containing said stacking direction.
 33. The stackableunit of claim 31, wherein the centering structure is arranged for actingin two directions perpendicular to each other and perpendicular to saidstacking direction.
 34. The stackable unit of claim 31, wherein saidguidance structure includes at least one wall having a foot, said atleast one wall extending in a direction parallel to the stackingdirection and being arranged for cooperating with at least one guidanceelement of said unit.
 35. The stackable unit of claim 34, wherein theguidance structure is formed on a gripping structure.
 36. The stackableunit of claim 34, wherein the guidance structure includes a pin.
 37. Thestackable unit of claim 31, wherein the guidance structure includes arear face having a foot, each of said rear faces being arranged forcooperating respectively with plates of another stackable unit of lowerrank.
 38. The stackable unit of claim 31, wherein the guidance structureincludes a rear face having arms of a gripping structure which saidstackable unit comprises, said faces being arranged to cooperaterespectively with plates of another stackable unit of higher rank. 39.The stackable unit of claim 31, wherein the centering structure includesat least two walls forming an arcuate angle with the vertical stackingdirection, said walls being arranged to respectively cooperate withcentering elements.
 40. The stackable unit of claim 39, wherein thecentering elements include bends on a gripping structure of said unit.41. The stackable unit of claim 39, wherein the centering elementsinclude bends which feet of said unit include.
 42. The stackable unit ofclaim 40, wherein the centering elements include pins which said unitincludes.
 43. The stackable unit of claim 40, wherein said walls areformed in feet of said unit.
 44. The stackable unit of claim 39, whereinthe centering structure includes at least two walls of the grippingstructure which said unit includes.
 45. The stackable unit of claim 31,wherein the centering structure includes beveled walls respectivelylocated on the faces turned towards a frame including feet which areintended to cooperate respectively with the upper edges of the sides ofthe frame of the second stackable unit.
 46. The stackable unit of claim31, wherein the centering structure includes beveled walls respectivelylocated on the faces turned towards the frame of gripping structurewhich said unit includes and arranged to cooperate respectively with thelower edges of the sides of the frame of another stackable unit ofhigher rank.
 47. The stackable unit of claim 31, wherein the supportstructure includes a seating wall and a pillar (a) substantiallyparallel to the stacking direction resting on said seating wall and (b)having a height equal to the distance between two stackable units minusthe thickness of the seating wall, the seating wall of a stackable unitbeing arranged to rest on the free end of a pillar of another stackableunit on which the stackable unit is arranged to rest.
 48. The stackableunit of claim 47, wherein said pillar has a cross-shaped cross-section.49. The stackable unit of claim 47, wherein said pillar has a U-shapedsection.
 50. The stackable unit of claim 46, wherein the seating wall isa wall having a foot having the shape of a U.
 51. The stackable unit ofclaim 47, wherein said pillar comprises a centering stud arranged toenter without play into a positioning hole which the frame forming saidstackable unit comprises.
 52. The stackable unit of claim 50, whereinsaid pillar comprises a centering stud arranged to enter without playinto a positioning hole which the frame forming said stackable unitcomprises, said pillar having a U-shaped section, and wherein said footincludes a centering stud centered with play parallel to the stackingdirection in a positioning hole which the frame forming said stackableunit comprises.
 53. The stackable unit of claim 31, wherein the distanceseparating a plane passing through an abutment and a plane passingthrough a holding-up structure of the support structure is equal to theheight of a cover added to the height of the foodstuff pressed by saidcover which is situated in the corresponding cell, with the thickness ofthe metal sheet being the bottom of said cell added to it.
 54. Thestackable unit of claim 31, wherein the gripping structure includes armsand feet, each arm and each foot respectively including folded metalstrips welded to opposite sides of a frame.
 55. The stackable unit ofclaim 54, wherein the posts are joined by a reinforcing bar welded byits ends to said posts.
 56. The stackable unit of claim 54, wherein saidmetal strips included on said arms and said foot are fixed on edges onthe frame.
 57. The stackable unit of claim 31 wherein the unit includesa frame with sides having openings for enabling passage of a sensor intothe cells.
 58. The stackable unit of claim 31, further includingprojections extending towards the outside of the stackable unit, theprojections enabling the unit to house sealed ends of some cooking bags.59. The stackable unit of claim 31, wherein the guiding structureincludes feet having posts that are not parallel to each other.
 60. Thestackable unit of claim 31, wherein the guiding structure includes feethaving posts, the distance separating a first post of the posts from asecond post of the posts being greater than the width of the pressingstructure.